Pointing devices for use with computers are well known. Existing pointing devices, such as mice and trackballs, combine tracking and selecting functions into one device. Tracking involves physically moving the mouse to control the motion of an on-screen pointer or other icon. Physical movement of the mouse is typically accomplished by moving the wrist and palm of the hand gripping the mouse. Once tracking has moved the pointer, an operation may be selected for execution by the computer, e.g., by depressing a button on the mouse or trackball.
A computer user relies significantly on his or her hand (particularly on the wrist, palm and fingers) to use a prior art pointing device for executing computer operations, and the user is required to have a certain level of hand/motor control. Unfortunately, a computer user with poor motor control, for example as a result of Parkinson's disease, or with poor eyesight, may have difficulty controlling his hand to position the pointer on-screen.
Repeated use of a conventional computer mouse can negatively impact even users with substantially unimpaired motor control. For instance, the use of a computer mouse over extended periods of time has been shown to be a leading cause of many different types of repetitive motion injuries (RMI) to body parts including the wrists, fingers, shoulders, and elbows, e.g., Carpal Tunnel Syndrome (CTS). Individuals in many fields of work rely on computers in their daily work and are thus forced to use a mouse quite extensively. Early injuries to children may even be incurable, rendering the injured child permanently disabled.